1. Field of the Invention
This invention relates generally to the field of exercise and rehabilitation, and more specifically, to an apparatus providing selective adjustment of the range of motion of a user's extremities, including either arms and legs, actively engaging in or passively participating in a cycling action.
2. Description of the Related Art
One of the most significant and the most common athletic injuries is to the knee, and published data continues to report at an incidence of between one-quarter and one-third of all men and women experience some type of knee injury annually. Approximately 10.8 million individuals visit a physician for knee injuries alone each year. Total estimated annual U.S. costs of all musculoskeletal conditions is $254 billion. Many injuries to the lower extremities of persons necessitate the use of rehabilitation exercises. Such injuries may include those to the joints of a person's leg (e.g., knee, hip), replacement of one's joint (e.g., total hip or knee arthroplasty [THA, TKA]), ligaments or tendons associated with these joints (e.g., anterior cruciate or medial collateral ligament [ACL, MCL], or patella or quadricepts tendons), or muscles of the leg (e.g., Rectus or biceps femoris, etc). Rehabilitation exercises are also frequently prescribed after surgery has been performed to further repair an injured site on a user's extremity.
Major trunk injuries are also exceedingly common in the United States. Major trunk injuries include those injuries that affect the shoulders and back. The shoulder joint, being the most flexible joint in the human body, can be easily injured because of accidentally over-extending the range of motion. The U.S. Department of Labor estimates that thirty-five percent of all muscoskeletal injuries are major trunk injuries. Over four million visits are made to health care professionals each year because of shoulder injuries. Moreover, the U.S. Department of Labor estimates that the average time off-work for shoulder injuries is twelve days. This corresponds to an estimated $13–20 billion due to time lost from work.
One common rehabilitation exercise recommended to improve muscle, ligament and tendon strength, and endurance for extremities post-injury or post-surgically, is movement in a cycling motion. The movement of a person's upper or lower extremity in a circular path induces motion in the articulations that form the shoulder and elbow or hip and knee, respectively. However, for rehabilitation to be effective, it must be tailored to the specific needs of a given person based on their physical size, type of injury, and plan for recovery, among other factors. For example, if a surgical repair has been made to a torn ACL of a person's leg, it is often desirable at the beginning of a rehabilitation regimen to limit the flexion or extension of the knew, due not only to pain, but also to avoid damage to the repair. Likewise, for the shoulder, a physician may recommend limiting the motion of the shoulder to something far less than its full capability of 360 degrees until natural recovery and sufficient rehabilitation has occurred. Although cycle-type exercise machines are recommended for use in certain rehabilitation regimens, they generally do not facilitate the adjustment of the range of motion of one individual extremity. Further, these machines are limited to the standard pedal or handle arrangement where one lever (handle or pedal) is offset from the other by 180 degrees around a hub. There are, however, rehabilitation regimens where benefits to flexibility, strength, and/or endurance are achieved by offsetting levers or handles at another angles for passive, assisted active, and active range of motion.